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Sidestep and Crossover Lower Limb Kinematics During a Prolonged Sport-Like Agility Test  

Authors: Potter D, Reidinger K, Szymialowicz R, Martin T, Dione D, Feinn R, Wallace D, Garbalosa J

Non-contact anterior cruciate ligament (ACL) injuries in athletes occur more typically towards the end of athletic competitions. However, the exact mechanisms of how prolonged activity increases the risk for ACL injuries are not clear. Therefore, the purpose of this study was to determine the effect of prolonged activity on the hip and knee kinematics observed during self-selected cutting maneuvers performed during a timed agility test.  Nineteen female Division I collegiate soccer players completed a self-selected cutting agility test until they were unable to meet a set performance time (one standard deviation less than the average baseline trial). Athletes performed either sidestep or crossover cuts. An effect of cut type and prolonged activity was seen at the hip and knee. During the prolonged activity trials, the knee was relatively more adducted and both the hip and knee were less flexed than during the baseline trials regardless of cut type. Irregardless of activity status, the hip was more internally rotated and abducted, and less flexed during sidestep cuts than during crossover cuts; the knee was more abducted and less flexed during the sidestep than crossover cuts. The authors concluded that during a sport-like agility test, prolonged activity appears to predispose the athlete to position their knee in a more extended and abducted posture and their hip in a more extended posture.  This position has been suggested to place stress on the ACL and potentially increase the risk for injury. Clinicians may want to consider the effects of prolonged activity on biomechanical risk factors for sustaining ACL injuries in the design of intervention strategies to prevent ACL injuries. 

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